The resource-intensive nature of the ruminant farming sector, which has been exacerbated by population growth and increasing pressure to reduce feed antibiotics and growth promoters, has sparked interest in looking for sustainable alternative feed sources to enhance ruminant production efficiency. Edible filamentous fungi, rich in macronutrients like proteins, offer promise in reducing the reliance on conventional protein sources and antimicrobials to improve feed quality and animal performance. The inclusion of single-cell proteins, particularly filamentous fungi, in ruminant feed has long been of scientific and industrial interest. This review focuses on the potential application of the extensively studied Aspergillus oryzae and its fermentation extracts in ruminant nutrition. It provides an overview of conventional ruminant feed ingredients, supplements, and efficiency. Additionally, this review analyzes the re-utilization of organic residues for A. oryzae cultivation and examines the effects of adding fungal extracts to ruminant feed on ruminal digestibility and animal performance, all within a circular bioeconomy framework.

Mycoprotein is an alternative protein produced through fungal fermentation. However, it typically relies on refined glucose syrup derived from starch, which can be costly and unsustainable. This study investigates the potential of soybean processing by-products (okara and soy whey) as alternative substrates for producing mycoprotein using Aspergillus oryzae. A. oryzae was cultured for 7 days at 30 °C in diluted okara (1:50) and soy whey (1:1) with or without agitation (100 rpm). Soy whey produced higher biomass yields (369.2-408.8 mg dry biomass/g dry substrate), but had a lower biomass concentration (0.783-0.867 g dry weight/L). Conversely, okara produced a higher biomass concentration (2.02 g dry weight/L) with a yield of 114.7 mg dry biomass/g dry substrate. However, biomass formation in okara was only observed in static conditions, as agitation caused biomass to entangle with soy pulp, hampering its production. Additionally, okara tended to release protein into the media, while soy whey accumulated protein within the biomass, reaching up to 53% w/w protein content. The results of this study provide a promising approach to addressing both soybean processing waste reduction and food security concerns.

We previously reported autophagy-mediated degradation of nuclei, nucleophagy, in the filamentous fungus Aspergillus oryzae. In this study, we examined whether nuclei are degraded as a whole. We generated A. oryzae mutants deleted for orthologs of Saccharomyces cerevisiae YPT7 and ATG15 which are required, respectively, for autophagosome-vacuole fusion and vacuolar degradation of autophagic bodies. Degradation of histone H2B-EGFP under starvation conditions was greatly decreased in the ΔAoypt7 and ΔAoatg15 mutants. Fluorescence and electron microscopic observations showed that autophagosomes and autophagic bodies surrounding the entire nuclei were accumulated in the cytoplasm of ΔAoypt7 and the vacuole of ΔAoatg15, respectively. These results indicate that nuclei are engulfed in the autophagosomes as a whole and transported/released into the vacuolar lumen where they are degraded.

Aspergillus flavus produces aflatoxin, a carcinogenic fungal toxin that poses a threat to the agricultural and food industries. There is a concern that the distribution of aflatoxin-producing A. flavus is expanding in Japan due to climate change, and it is necessary to understand what types of strains inhabit. In this study, we sequenced the genomes of four Aspergillus strains isolated from agricultural fields in the Ibaraki prefecture of Japan and identified their genetic variants. Phylogenetic analysis based on single-nucleotide variants revealed that the two aflatoxin-producing strains were closely related to A. flavus NRRL3357, whereas the two non-producing strains were closely related to the RIB40 strain of Aspergillus oryzae, a fungus widely used in the Japanese fermentation industry. A detailed analysis of the variants in the aflatoxin biosynthetic gene cluster showed that the two aflatoxin-producing strains belonged to different morphotype lineages. RT-qPCR results indicated that the expression of aflatoxin biosynthetic genes was consistent with aflatoxin production in the two aflatoxin-producing strains, whereas the two non-producing strains expressed most of the aflatoxin biosynthetic genes, unlike common knowledge in A. oryzae, suggesting that the lack of aflatoxin production was attributed to genes outside of the aflatoxin biosynthetic gene cluster in these strains.

This study addresses the challenge of enhancing gamma-aminobutyric acid (GABA) content in soy sauce through optimized fermentation condition. Using a multiple starter culture, consisting of Aspergillus oryzae strain NSK, Bacillus cereus strain KBC and Tetragenococcus halophilus strain KBC, the incubation conditions including the percentage of bacterial inoculum (10, 15 and 20 %), pH (3, 5 and 7) and agitation speed (100, 150 and 200 rpm) were optimized through Response Surface Methodology (RSM). Under the optimal conditions (20 % inoculum, pH 7 and stirring at 100 rpm), the multiple starter culture generated 128.69 mg/L of GABA after 7 days and produced 239.08 mg/L of GABA after 4 weeks of fermentation, which is 36 % higher than under non-optimized conditions (153.48 mg/L). Furthermore, sensory analysis revealed high consumer acceptance of the fermented soy sauce than the control (soy sauce without any treatment and additional bacteria) and commercial soy sauce. Consumers indicated that the starter culture offered an improved umami taste and reduced bitter, sour and salty flavours compared to the commercial product. Under optimal fermentation conditions determined by RSM statistical analysis, the multiple starter culture is able to produce high levels of GABA and is more likely to be accepted by consumers. The findings of this research have the potential to impact the food sector by offering a functional soy sauce with added health benefits and also being well-received by consumers.

Solid-state fermentation (SSF) and extrusion are effective methods to improve the nutritional and sensory quality of rice bran. The effect of the processing sequence of SSF and extrusion and microbial strains on the quality of rice bran was studied. The results showed that the first SSF followed by extrusion increased the contents of phenolic, flavonoid and γ-oryzanol, but the color changed to brown. The first extrusion followed by SSF caused damage to bioactive components and antioxidant activity, but significantly increased the content of arabinoxylans. The difference between the two processing sequences may be related to the process time and the effect of substrate on microbial induction. Aspergillus oryzae and Neurospora sitophila were suitable for increasing the bioactive components of rice bran, while Lactiplantibacillus plantarum was suitable for increasing water-extractable arabinoxylan content. Different processing sequences and microbial strains have their advantages, and these results can provide reference for rice bran processing.

Aflatoxins (AFs) are carcinogenic fungal toxins contaminating up to 25% of the global food supply. Over half of the world\'s population is exposed to unmonitored levels of AFs, mostly aflatoxin B1 (AFB1). Despite numerous efforts over the past 60 years, there are no solutions to remove AFs safely from food. Here, we present a safe and effective AF-degrading product called \"D-Tox\", a filtered culture broth of Aspergillus oryzae grown in a food-grade liquid medium. When 5 ppm of AFB1 is added to D-Tox, ∼90% is degraded at 48 and 24 hr at room temperature and 50°C, respectively. Moreover, when varying amounts (0.1 ppm ∼ 100 ppm) of AFB1 are added to D-Tox at 100°C, over 95% of AFB1 is degraded in 1 hr, suggesting a nonenzymatic process. Examining degradation of 100 ppm AFB1 reveals that aflatoxin D1 (AFD1) is the major transient degradant of AFB1, indicating that degradation occurs irreversibly by lactone ring hydrolysis followed by decarboxylation. D-Tox further degrades AFD1 to unknown fragmented products. Importantly, the practical application of D-Tox is also demonstrated, as more than 70% of AFB1 is degraded when wheat, corn, and peanuts naturally contaminated with high levels of AFB1 (0.3 ∼ 4.5 ppm) are boiled in D-Tox for 1 hr. Additionally, D-Tox can degrade other lactone-ring containing mycotoxins, including patulin and ochratoxin. D-Tox exhibits no cytotoxicity under the conditions tested in MCF-7 breast cancer cell lines. In summary, D-Tox is a safe and effective AF-detoxifying product that can enhance global food safety.

Amazake is a traditional, sweet, non-alcoholic Japanese beverage typically produced through koji fermentation by the fungus Aspergillus oryzae. However, alternative microorganisms such as Bacillus amyloliquefaciens offer potential advantages and novel possibilities for producing similar fermented beverages. This study aimed to replicate the ancestral beverage of amazake by replacing A. oryzae (W-20) with B. amyloliquefaciens (NCIMB 12077) and comparing their fermentation processes and resulting products. Our results show that the production of amazake with B. amyloliquefaciens (ABA) is not only possible but also results in a beverage that is otherwise distinct from traditional amazake (AAO). Saccharification was achievable in ABA at higher temperatures than in AAO, albeit with lower reducing sugar and enzymatic activity values. Amino acids and organic acids were more abundant in AAO, with cysteine being uniquely present in AAO and shikimic acid only being present in ABA. The volatile aroma compound profiles differed between the two beverages, with AAO exhibiting a greater abundance of aldehydes, and ABA a greater abundance of ketones and alcohols. Interestingly, despite these compositional differences, the two beverages showed similar consumer panel acceptance rates. An analysis of their microbial communities revealed pronounced differences between the amazakes, as well as temporal changes in ABA but not in AAO. This study provides promising insights into harnessing the potential of B. amyloliquefaciens as the primary microorganism in the fermentation process of amazake-like beverages, marking an important advancement in the field of fermented low-alcohol beverage production, with possible applications in other fermented foods.

Here we describe a complex enzymatic approach to the efficient transformation of abundant waste chitin, a byproduct of the food industry, into valuable chitooligomers with a degree of polymerization (DP) ranging from 6 to 11. This method involves a three-step process: initial hydrolysis of chitin using engineered variants of a novel fungal chitinase from Talaromyces flavus to generate low-DP chitooligomers, followed by an extension to the desired DP using the high-yielding Y445N variant of β-N-acetylhexosaminidase from Aspergillus oryzae, achieving yields of up to 57%. Subsequently, enzymatic deacetylation of chitooligomers with DP 6 and 7 was accomplished using peptidoglycan deacetylase from Bacillus subtilis BsPdaC. The innovative enzymatic procedure demonstrates a sustainable and feasible route for converting waste chitin into unavailable bioactive chitooligomers potentially applicable as natural pesticides in ecological and sustainable agriculture.

Rice wine, well known for its unique flavor, rich nutritional value, and health benefits, has potential for extensive market development. Rhizopus and Aspergillus are among several microorganisms used in rice wine brewing and are crucial for determining rice wine quality. The strains were isolated via Rose Bengal and starch as a combined separation medium, followed by oenological property and sensory evaluation screening. The strain exhibiting the best performance can be screened using the traditional rice wine Qu. The strains YM-8, YM-10, and YM-16, which exhibited strong saccharification and fermentation performance along with good flavor and taste, were obtained from traditional rice wine Qu. Based on ITS genetic sequence analysis, the YM-8, YM-10, and YM-16 strains were identified as Rhizopus microsporus, Rhizopus arrhizus, and Aspergillus oryzae. The optimum growth temperature of each of the three strains was 30°C, 32°C, and 30°C, and the optimum initial pH was 6.0, 6.5, and 6.5, respectively. The activities of α-amylase, glucoamylase, and protease of YM-16 were highest at 220.23±1.88, 1,269.04±30.32, and 175.16±1.81 U/g, respectively. The amino acid content of rice wine fermented in a 20-L bioreactor with the three mold strains was higher than that of the control group, except for arginine, which was significantly lower than that of the control group. The total amino acid content and the total content of each type of amino acid were ranked as YM-16 > YM-8 > YM-10 > control group, and the amino acid content varied greatly among the strains. The control group had a higher content, whereas YM-8 and YM-16 had lower contents of volatile aroma components than the control group and had the basic flavor substances needed for rice wine, which is conducive to the formation of rice wine aroma. This selected strain, YM-16, has strong saccharification and fermentation ability, is a rich enzyme system, and improves the flavor of rice wine, thereby demonstrating its suitability as a production strain for brewing.